In the vulcanization process, a green tire is disposed within a tire mold installed in a vulcanizer, and a bladder for tire vulcanization is inserted into the green tire in a deflated state. Then, a heating medium and a pressurizing medium are injected into the bladder with a mold in a closed state to expand the bladder and vulcanize the green tire.
The bladder has a cylindrical shape with relatively thick clamps parts positioned around the periphery of two end openings of the bladder. In order to assemble this bladder into the vulcanizer, a bladder assembly is manufactured with the clamp parts sandwiched between ring parts.
In the related art, to manufacture the bladder assembly, first, the bladder is set in an upright position with the two end openings being on the upper side and the lower side, and a ring part is attached to one of the clamp parts located on the upper side. Next, the bladder is inverted vertically so that the other clamp part is on the top side. Then, the ring part is attached by sandwiching the clamp part on the other side, to complete the bladder assembly. The ring parts are made of metal and have corresponding weight, thus, inverting the bladder vertically requires a lot of labor and time.
Thus, a bladder inversion device has been proposed in order to reduce the labor and increase the operational efficiency of the bladder inversion operation (for example, see Japanese Unexamined Patent Publication No. 2010-89474). However, the proposed inversion device includes a mechanism for inverting the bladder vertically, so the device is correspondingly large, and a strong driving force is needed. Thus, there is a problem that the inversion device is large-scale. Also, vertically inverting the bladder itself requires a certain amount of time, and this is a hindrance to improving the productivity of the bladder assembly.